Introduction:

For this experiment, we measured the long-term effect of SARS-CoV-2 on human taste receptors. The primary organ for taste is the tongue. The tongue contains small, raised bumps that are called papillae. Each of these papillae possess a set of taste receptor cells that are able to differentiate between various taste sensations such as salt, sugar, and sour. Once these substances are detected, the taste receptor cells then transmit this information to gustatory nerves, who then transmit this information to the central nervous system, and ultimately the brain (Cuenca, 2013). The National Health Service of England states that their research has shown so far that among people who have tested positive for COVID-19, 1 in 10 cases have reported smell and taste problems that have persisted after infection (Evangalou et al., 2021). Thus, for our experiment, we are testing to see what the long-term effects on taste receptors are for those who have tested positive for COVID-19 in the past year.

Hypothesis:

We believe that those who have tested positive for COVID-19 will experience a dulling of taste sensation in their taste receptors. We do not believe that gender will make a difference in the results of this experiment. Age may also play a factor in this test, possibly causing sensation to dull as well.

Materials and Methods:

For this experiment, we surveyed a total of 23 people between the ages of 23 and 56. 13 of the participants were male, and 10 were female. 12 of the volunteers have tested positive for Covid-19 within the past year, the remaining 11 have no history of Covid-19. We used Lay’s Original

potato chips to test salty taste receptors, Original flavored Skittles to test sweet taste receptors, and Sour flavored Skittles to test sour taste receptors (Photo 1-A). Each participant was tested in private, and had their eyes covered (Photos 1-B-1-D). The participants were offered the test items one at a time and asked to state if the item was sweet (Photo 1-C), salty (Photo 1-D), or sour (Photo 1-B). Then they were asked to rate the strength of the taste on a scale of 1-5, with 1 being barely detectable and 5 being extremely detectable.

Discussion  

During our research we learned that what we expected somewhat agreed with our research.  Many Covid+ participants rated the sour skittles lower on the rating scale (see graphs 1 & 3), where the Covid – participants rated the sour skittles high (see graph 2 & 4). We believe that this could be caused form chemosensory dysfunction which is one of the chief symptoms of SAS-CoV2 infections (Srinivasan M, 2021).  Covid – participants rated the sour skittles on average 4.5 for men and 4 for women out of a 1-5 range.  Whereas Covid + participants rated the sour skittles on average 2 for both men and women.  

The one thing unique about this disruption is that normally taste is not affected without olfactory disruptions as well. This direct impact on taste is separate from the loss of smell with Covid and shows that difference ACE receptors can be related to individual taste receptors without disruption to the olfactory system (Boscolo-Rizzo P, et al, 2022).   

Gender and age are still a possible contributor to the variance of loss.  During another clinical trial women were 11% more likely than men to report a loss of smell and taste. About 73% of those who reported a loss of smell and taste were ages 26-35 (Crist, C., 2022). With our limited amount of data our study cannot support this claim.  

Besides the limited number of subjects, other factors that could have effects on our results were how severe the participant had Covid and other lifestyle habits such as general hygiene of the mouth and smoking.  The rating scale could also be skewed person to person based off individual eating habits, diet and opinion.  

Conclusion 

Before starting this trial, we believed that those who have tested positive for COVID-19 will experience a dulling of taste sensation in their taste receptors. We did not believe that gender will make a difference in the results of this experiment. Age may also play a factor in this test, possibly causing sensation to dull as well. After reviewing the data, we can support that certain taste receptors are affected and have a dulled affect (review the above graphs 1-4 for sour ratings).  Even though our limited number of research subjects cannot support the gender or age differences that we expected, other research we found shows that age and gender CAN make a difference.  

References 

Boscolo-Rizzo P, et al (2022) Comprehensive chemosensory psychophysical evaluation of self- reported gustatory dysfunction in patients with long-term COVID-19: a cross-sectional study. JAMA Otolaryngol Head Neck Surg. Retrieved April 26, 2022, from https://www.medpagetoday.com/infectiousdisease/covid19/96549 

Crist, C. (2022, January 18). Study finds genetic factor for Covid Smell and taste loss.    WebMD. Retrieved April 16, 2022, from https://www.webmd.com/lung/news/20220118/study-finds-genetic-factor-covid-smell-taste-loss  

Cuenca, L. (2013, August 12). The bittersweet truth of sweet and bitter taste receptors.     Science in the News. Retrieved April 14, 2022, from https://sitn.hms.harvard.edu/flash/2013/the-bittersweet-truth-of-sweet-and-bitter-taste-receptors/  

Evangalou, N., Mustapa, F. M., Levell, N., Bleiker, T., Llyod, J., Walker, L., Cunningham, L., Crudgington, K., Holmes, S., Dawson, C., & Singh, S. (2021, December). Your COVID recovery- Your taste and smell changes. NHS choices. Retrieved April 14, 2022, from https://www.yourcovidrecovery.nhs.uk/managing-the-effects/effects-on-your-body/taste-and-smell/  

Srinivasan M (2021) Taste Dysfunction and Long COVID-19. Frontiers in Cellular and Infection Microbiology. Retrieved April 16,2022, from https://www.frontiersin.org/articles/10.3389/fcimb.2021.716563/full